CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Parenthetical) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Fair value of held-to-maturity securities	$ 8,393,000	$ 10,349,000
Allowance for loan losses	$ 46,063,000	$ 36,001,000
Debt Instrument [Line Items]
Preferred stock shares authorized (in shares)	5,000,000	5,000,000
Preferred stock shares issued (in shares)	0	0
Preferred stock shares outstanding (in shares)	0	0
Common stock shares authorized (in shares)	100,000,000	100,000,000
Common stock shares issued (in shares)	52,410,053	55,999,754
Common stock shares outstanding (in shares)	52,410,053	55,999,754
Senior Unsecured Term Notes, September 2014 \| Senior Unsecured Term Notes
Debt Instrument [Line Items]
Principal	$ 95,000,000	$ 95,000,000
Debt interest rate	6.50%
Unamortized debt issuance costs	$ 491,000	$ 584,000

The maximum number of common shares permitted to be issued by an entity's charter and bylaws.

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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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Face (par) amount of debt instrument at time of issuance.

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Contractual interest rate for funds borrowed, under the debt agreement.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

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Fair value of investment in debt security measured at amortized cost (held-to-maturity).

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Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

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The maximum number of nonredeemable preferred shares (or preferred stock redeemable solely at the option of the issuer) permitted to be issued by an entity's charter and bylaws.

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